DESCRIPTION (Investigator's Abstract): 1) The major goal of the research program is to use anatomical, histochemical, and electrophysiological methods to determine how the visual system is subdivided into areas, nuclei, and modules, and how these subdivisions are interconnected in a range of primate taxa. This approach will indicate what features of organization are general in primates, and thus likely to be present in humans, as well as identify elaborations and specializations where further study could provide concepts of function that would be difficult to obtain directly from humans. Both visual and polysensory areas of the occipital, temporal, and parietal lobes, and well as visual and visuomotor areas of the frontal lobe will be studied. 2) Related studies will evaluate concepts of hierarchical processing in the visual system, and determine the potential for plasticity and recovery from damage in the adult visual system by recording from visual area immediately and weeks to months after lesions remove important inputs to those areas. These studies will provide information about the functional consequences of damage to the human visual system, as well as about the extent and time course of recovery from such damage. 3) A third set of experiments will use in vivo and in vitro preparation to determine the detailed structure of connections, specifically the extent, shapes, and types of terminal arbors of input axons. This information is seen as critical to the development of theories of functional recovery after restricted lesions of the adult and developing visual system, as well as theories of the roles of environmental factors in the development of the visual system.